1. Field of the Invention
The invention relates to nano-scale structures and, more specifically, to a method of making nano-structures by carbon nanotube confined reactions.
2. Description of the Prior Art
Field emission devices (gated or ungated) have applications in X-ray imaging systems, displays, electronics, microwave amplifiers, fluorescent lamp cathodes, gas discharge tubes, and many other electrical systems. Other applications for field emission devices include sensors, photonic bandgap devices, and wide bandgap semiconductor devices.
Carbon nanotubes are currently being researched as electron emission sources in, for example, flat panel field emission display applications, microwave power amplifier applications, transistor applications and electron-beam lithography applications. The carbon nanotubes are typically synthesized through an arc discharge method, a chemical vapor deposition (CVD) method or a laser ablation method. Carbon nanotubes offer the advantage of having high aspect ratios which increases the field enhancement factor and therefore the extraction of electrons at relatively low electric fields. Carbon nanotubes, however, exhibit a fairly high work function, and are prone to damage under typical operating conditions, limiting the life and effectiveness of the devices. What is needed, therefore, is a material more robust and with a lower work function than carbon, but with a cylindrical geometry and diameters in the 10-800 nm range.
Metal carbide nanorods are candidate materials for use in field emission gated devices, which have applications in stationary computed tomography systems, displays, etc. A fabrication procedure is required that allows for seamless integration with gated device structures as well as control of the lateral density of nanorods so that electric field shielding does not occur. Carbide materials may be preferred due to their chemical stability, mechanical hardness and strength, high electrical conductivity, and relatively low work function. These characteristics make them particularly suited to the environment that may be found in a computed tomography system and the like. Such materials may also be important in superconducting nanodevices, optoelectronic nanodevices, display systems, lighting systems and other similar systems.
The main approach to synthesizing carbide nanorods to date has been to use a carbon nanotube (CNT) as a template on which a reaction is carried out between the CNT and a metal, metal oxide, or metal iodide in vapor form to produce metal carbide nanorods. This process is typically done in a vacuum-sealed tube with reaction times being more than 24 hours. However, demonstration of CNT conversion on a substrate such as silicon or in a device structure is not known.
Therefore, there is a need for a system that generates metallized carbon nanostructures from a substrate in a relatively short period of time.
There is also a need for a system that grows elongated nanostructures in situ directly in device structures.